(VAR x y )
(RULES 
        f(0) -> true
        f(1) -> false
        f(s(x)) -> f(x)
        if(true, x, y) -> x
        if(false, x, y) -> y
        g(s(x), s(y)) -> if(f(x), s(x), s(y))
        g(x, c(y)) -> g(x, g(s(c(y)), y))
        
)